Objectives: (a) To develop, standardize, and evaluate sensitive and specific assays for antibodies to Bordetella pertussis antigens. (b) To serve as a refer-ence laboratory for pertussis serology by writing reference methods, procuring reference reagents, training visiting personnel, and performing comparative test-ing with outside laboratories. For all assays listed below, protocols have been distributed, visitors were trained, and comparative testing with outside laboratories has been performed. (1) Microagglutination assay: Because the supply of US Reference Antigen for Pertussis Microagglutination Assay, Lot 1 is nearly depleted, preparation of Lot 2 has been initiated by propagating sufficient B. pertussis bacteria for 2000 vials of antigen. Lyophilization and testing of Lot 2 should be completed before Oct. 1, 1990. (2) CHO-Cell Neutralization Assay: Stained and dried demonstration plates have been prepared and are available for distribution to collaborators. (3) ELISA Assays: (a) Control preparations (300 mg each) of pertussis toxin (PT) and filamentous hemagglutinin (FHA) were purchased after extensive comparative testing of preparations from several different commercial sources. These are now available for distribution. (b) In order to meet LOP testing requirements, 69kDa protein (100 gm) and fimbriae (50 mg) were purchased after confirmation of reagent purity. (c) Reference Pertussis Antiserum (human) Lot 3 was determined to be acceptable for some, but not all assays performed by the LOP. Lot 4 (1000 ampoules) has been lyophilized, tested, and designated reference serum for the anti-69kDa antibody assays. Sufficient serum for Lot 5 has been obtained, and is being prepared specifically as a reference for the IgA anti-PT assay. (d) Collaboration with scientist at the SBL has continued to assess the within laboratory reproducibility and between laboratory comparability of results using a standardized ELISA procedure. (e) Evaluation of a new ELISA calculation program has continued.